Vincent Whitchurch | 3117ff1 | 2019-04-03 13:33:27 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
| 3 | * Copyright (C) 2019 Axis Communications AB |
| 4 | * |
| 5 | * Based on ttyprintk.c: |
| 6 | * Copyright (C) 2010 Samo Pogacnik |
| 7 | */ |
| 8 | |
| 9 | #include <linux/console.h> |
| 10 | #include <linux/module.h> |
| 11 | #include <linux/tty.h> |
| 12 | |
| 13 | static const struct tty_port_operations ttynull_port_ops; |
| 14 | static struct tty_driver *ttynull_driver; |
| 15 | static struct tty_port ttynull_port; |
| 16 | |
| 17 | static int ttynull_open(struct tty_struct *tty, struct file *filp) |
| 18 | { |
| 19 | return tty_port_open(&ttynull_port, tty, filp); |
| 20 | } |
| 21 | |
| 22 | static void ttynull_close(struct tty_struct *tty, struct file *filp) |
| 23 | { |
| 24 | tty_port_close(&ttynull_port, tty, filp); |
| 25 | } |
| 26 | |
| 27 | static void ttynull_hangup(struct tty_struct *tty) |
| 28 | { |
| 29 | tty_port_hangup(&ttynull_port); |
| 30 | } |
| 31 | |
| 32 | static int ttynull_write(struct tty_struct *tty, const unsigned char *buf, |
| 33 | int count) |
| 34 | { |
| 35 | return count; |
| 36 | } |
| 37 | |
Jiri Slaby | 03b3b1a | 2021-05-05 11:19:15 +0200 | [diff] [blame] | 38 | static unsigned int ttynull_write_room(struct tty_struct *tty) |
Vincent Whitchurch | 3117ff1 | 2019-04-03 13:33:27 +0200 | [diff] [blame] | 39 | { |
| 40 | return 65536; |
| 41 | } |
| 42 | |
| 43 | static const struct tty_operations ttynull_ops = { |
| 44 | .open = ttynull_open, |
| 45 | .close = ttynull_close, |
| 46 | .hangup = ttynull_hangup, |
| 47 | .write = ttynull_write, |
| 48 | .write_room = ttynull_write_room, |
| 49 | }; |
| 50 | |
| 51 | static struct tty_driver *ttynull_device(struct console *c, int *index) |
| 52 | { |
| 53 | *index = 0; |
| 54 | return ttynull_driver; |
| 55 | } |
| 56 | |
| 57 | static struct console ttynull_console = { |
| 58 | .name = "ttynull", |
| 59 | .device = ttynull_device, |
| 60 | }; |
| 61 | |
Vincent Whitchurch | 3117ff1 | 2019-04-03 13:33:27 +0200 | [diff] [blame] | 62 | static int __init ttynull_init(void) |
| 63 | { |
| 64 | struct tty_driver *driver; |
| 65 | int ret; |
| 66 | |
| 67 | driver = tty_alloc_driver(1, |
| 68 | TTY_DRIVER_RESET_TERMIOS | |
| 69 | TTY_DRIVER_REAL_RAW | |
| 70 | TTY_DRIVER_UNNUMBERED_NODE); |
| 71 | if (IS_ERR(driver)) |
| 72 | return PTR_ERR(driver); |
| 73 | |
| 74 | tty_port_init(&ttynull_port); |
| 75 | ttynull_port.ops = &ttynull_port_ops; |
| 76 | |
| 77 | driver->driver_name = "ttynull"; |
| 78 | driver->name = "ttynull"; |
| 79 | driver->type = TTY_DRIVER_TYPE_CONSOLE; |
| 80 | driver->init_termios = tty_std_termios; |
| 81 | driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET; |
| 82 | tty_set_operations(driver, &ttynull_ops); |
| 83 | tty_port_link_device(&ttynull_port, driver, 0); |
| 84 | |
| 85 | ret = tty_register_driver(driver); |
| 86 | if (ret < 0) { |
Jiri Slaby | 9f90a4d | 2021-07-23 09:43:16 +0200 | [diff] [blame] | 87 | tty_driver_kref_put(driver); |
Vincent Whitchurch | 3117ff1 | 2019-04-03 13:33:27 +0200 | [diff] [blame] | 88 | tty_port_destroy(&ttynull_port); |
| 89 | return ret; |
| 90 | } |
| 91 | |
| 92 | ttynull_driver = driver; |
| 93 | register_console(&ttynull_console); |
| 94 | |
| 95 | return 0; |
| 96 | } |
| 97 | |
| 98 | static void __exit ttynull_exit(void) |
| 99 | { |
| 100 | unregister_console(&ttynull_console); |
| 101 | tty_unregister_driver(ttynull_driver); |
Jiri Slaby | 9f90a4d | 2021-07-23 09:43:16 +0200 | [diff] [blame] | 102 | tty_driver_kref_put(ttynull_driver); |
Vincent Whitchurch | 3117ff1 | 2019-04-03 13:33:27 +0200 | [diff] [blame] | 103 | tty_port_destroy(&ttynull_port); |
| 104 | } |
| 105 | |
| 106 | module_init(ttynull_init); |
| 107 | module_exit(ttynull_exit); |
| 108 | |
| 109 | MODULE_LICENSE("GPL v2"); |